1. Field of the Invention
The present invention relates to a Plasma Display Panel (PDP) and a method of manufacturing a back panel of the PDP, and more particularly, to a PDP that forms an image by applying a discharge voltage to a plurality of electrodes arranged on two substrates facing each other to generate ultraviolet rays which excite phosphor layers and a method of manufacturing the back panel.
2. Description of the Related Art
Plasma display panels (PDPs) can be classified into Direct Current (DC) PDPs and Alternating Current (AC) PDPs. In the DC PDP, electrodes are exposed in a discharging space, and charged particles move directly between the corresponding electrodes. In the AC PDP, at least one electrode is covered by a dielectric layer, and a discharge occurs using an electric field of a wall charge instead of a charge directly moving between the electrodes.
An AC PDP includes a front panel and a back panel. The front panel includes a front plate. X electrodes and Y electrodes are arranged in pairs on the front plate, and address electrodes crossing the X and Y electrodes are arranged on a surface of a back plate facing the front plate. The X and Y electrodes on the front plate are transparent electrodes made of Indium-Tin-Oxide (ITO), and are also referred to as transparent electrodes. In addition, bus electrodes, which are formed of metal and have narrow widths for reducing line resistance, are arranged on an upper portion of the transparent electrodes. A discharge space forming a unit discharge cell is defined by a pair of X and Y electrodes and the address electrode crossing the pair of X and Y electrodes.
A front dielectric layer and a back dielectric layer are arranged on the front plate where the X and Y electrodes are arranged and on the surface of the back plate where the address electrodes are arranged to cover the electrodes. A protective layer is arranged on the front dielectric layer, and a barrier rib that maintains a discharge distance and prevents cross-talk between discharge cells is arranged on the back dielectric layer. Red, green, and blue phosphor layers are arranged on both surfaces of the barrier rib and an upper surface of the back dielectric layer where the barrier rib is not formed. The front panel and the back panel are sealed by a sealing unit, for example, a frit.
When a discharge cell is selected for emitting light, a predetermined voltage is applied to the address electrode and the Y electrode of the selected discharge cell. Then, an address discharge. occurs and a wall charge is generated on the front dielectric layer. When a predetermined voltage is applied between the X electrode and the Y electrode, the wall charge moves between the two electrodes to cause the discharge gas to undergo a sustaining discharge and to generate ultraviolet rays. Then, the ultraviolet rays excite the phosphor layer to form an image.
A PDP can be divided into an image area H that can display an image and a non-image area N that cannot display an image. On the image area H, the address electrodes, the X electrodes, and the Y electrodes are connected to a driving circuit that drives the address electrodes and the X and Y electrodes, and accordingly, the image can be displayed in response to signals from the driving circuit. On the non-image area N, at least one of the address electrode, the X electrode, and the Y electrode is not connected to the driving circuit so that an image cannot be displayed there. The back panel 30 includes a back plate terminal area C, on which the address electrodes are connected to a driving unit that drives the address electrodes.
A ventilation hole is arranged in the non-image area N.
The ventilation hole, coupled with a ventilation pipe that is arranged on a back surface of the back plate, simultaneously serves as a path through which gas remaining in an outer part of the PDP can be discharged after joining the front plate and the back plate, and as a path through which the remaining gas that is generated in fabricating the front plate and the back plate and joining the plates can be exhausted to the ventilation pipe and a gas, such as Ne or Xe, can enter the PDP. Thus, the ventilation hole, together with the ventilation pipe, performs both a vacuum induction role and a gas path role.
However, the ventilation hole of the PDP is formed by a hole forming unit, such as a drill, from the upper surface of the back panel 30 to the lower surface, or in the opposite direction. Thus, when the operation of forming the hole in the back plate is completed, the back plate becomes more vulnerable to damage. Specifically, the surface of the back plate becomes rough, and the area around the ventilation hole is prone to cracking.
In addition, only one back plate is fabricated from a base plate and a remaining portion of the base plate that is not included in the back plate is discarded. This increases manufacturing overhead of the back plate.
In order to solve the above problem, recently, one base plate is cut to manufacture a plurality of back plates. Thus, the excluded portion of the base plate can be reduced, and the manufacturing cost of the back plate can be reduced.
However, when the ventilation hole is not distanced from the cut by more than a predetermined threshold length, the area around the ventilation hole is even more prone to cracking, and the back plate can be damaged. Specifically, since an end portion of the back plate is coupled to a jig during manufacture and handling, stress is applied to the crack, and the back plate can be damaged more.